baller95 Posted March 21, 2016 Author Report Share Posted March 21, 2016 The port volume and driver displacement will subtract from the volume so the overall size will need to be bigger to account for this. Net volume is the empty space thats left after you account for everything else that inside the box, this includes the space the sub takes up, the port, and any bracing. For example if you had a box that had internal dimensions 12" x 12" x 24", it would have 2 cu ft of gross volume. Lets say the sub takes up .1 cu ft, the port takes up .45 cu ft, and bracing takes up .05 cu ft. The net volume would be 1.4 cu ft. Ok thanks. I'm confused as to how to use WinISD to find dimensions for a port without knowing what port volume I'll have. Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted March 21, 2016 Report Share Posted March 21, 2016 This is where Torres is going to be more useful than WinISD is. From WinISD you know you want 2.6 cubes of net airspace and 33.5 sq in of port tuned to 34 Hz. You can use Torres to help you come up with a box layout that has those parameters and fits in your space (hopefully). "Nothing prevents people from knowing the truth more than the belief they already know it.""Making bass is easy, making music is the hard part."Builds: Link to comment Share on other sites More sharing options...
baller95 Posted March 25, 2016 Author Report Share Posted March 25, 2016 Alright I think I'm finally done! So this should be tuned to 34 Hz, with an net volume of 2.55 ft^3. My goal was 2.6 ft^3 but I'm happy with this. Also double baffled the front. I did not remove 0.75" from my port length to account for the extra baffle in the sketch below but I'll remember to do it when I build the box. WinISD is telling me that I should see 120.7 dB @ 42.2 Hz which is pretty decent. Port air velocity is around 82 ft/s @ 32 Hz which is ok. Overall I'm happy. Hopefully it ends up sounding good! Link to comment Share on other sites More sharing options...
baller95 Posted March 25, 2016 Author Report Share Posted March 25, 2016 Just wondering, is it not a good idea to have the left sub is positioned in front of the port wall and the right in front of the back wall? Link to comment Share on other sites More sharing options...
ckeeler11 Posted March 25, 2016 Report Share Posted March 25, 2016 Im no expert but there is a potential for one of the subs to unload more than the other with that configuration. that is one reason that a center port would be better, the port would line up the same for both subs. Also remember that the port length is calculated from the centerline of the port. the 120 db winisd tells you does not account for cabin gain so could be louder. Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted March 25, 2016 Report Share Posted March 25, 2016 Just wondering, is it not a good idea to have the left sub is positioned in front of the port wall and the right in front of the back wall? You should be fine. Lots of boxes are done the way you have it. The only thing I'd do would be to add a brace running from your front panel between your two subs, back to the port panel. "Nothing prevents people from knowing the truth more than the belief they already know it.""Making bass is easy, making music is the hard part."Builds: Link to comment Share on other sites More sharing options...
baller95 Posted March 25, 2016 Author Report Share Posted March 25, 2016 Im no expert but there is a potential for one of the subs to unload more than the other with that configuration. that is one reason that a center port would be better, the port would line up the same for both subs. Also remember that the port length is calculated from the centerline of the port. the 120 db winisd tells you does not account for cabin gain so could be louder. Makes sense. Shit. At least knowing I might get more than 120 dB is good news LOL. You should be fine. Lots of boxes are done the way you have it. The only thing I'd do would be to add a brace running from your front panel between your two subs, back to the port panel. Yeah I was definitely planning on putting bracing there. Now that I somewhat know what I'm doing I'll try making another version and try to see if I can get a good net 1.3 ft^3 per sub with two ports and having each sub isolated. It'll basically be two separate sub boxes joined together. Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted March 25, 2016 Report Share Posted March 25, 2016 If you want to do separate chambers, that's fine. You will most likely get slightly better performance with a single chamber and port though. "Nothing prevents people from knowing the truth more than the belief they already know it.""Making bass is easy, making music is the hard part."Builds: Link to comment Share on other sites More sharing options...
baller95 Posted March 25, 2016 Author Report Share Posted March 25, 2016 If you want to do separate chambers, that's fine. You will most likely get slightly better performance with a single chamber and port though.Hmm, interesting. Well I'm done version 2 so let me know what you guys think is best overall! Each chamber has a net volume of 1.28 ft^3 so a total net of 2.56 ft^3 minus bracing. Again tuned to 34 Hz. Port dimensions for this is 12.50" H * 1.664" W * 33.37" L for each port. This one has nearly 2 extra inches of port length per sub compared to my single ported design (12.50" H * 3.33" W * 31.53" L) for some reason.2D - 3D - Hehehe Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted March 25, 2016 Report Share Posted March 25, 2016 That box looks really nice! Looks like you have SketchUp pretty well figured out. I would use the design with a single chamber and slot port though. The ports in your dual chamber design have two 180 degree turns in them vs the single 90 degree turn in the common chamber box. Also the dual ports have a lot higher aspect ratio, so they have move internal surface area for an equal amount of port area. Both of these things will cause additional air resistance, which is not what you want. If you want to stick with a dual chamber design. I'd increase the port area by 20% and try to reconfigure the ports to get rid of those 180 degree turns. "Nothing prevents people from knowing the truth more than the belief they already know it.""Making bass is easy, making music is the hard part."Builds: Link to comment Share on other sites More sharing options...
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